Conventional anaerobic adhesives are prepared by adding an organic peroxide, a gelation stabilizer, etc., to a polyfunctional methacrylate as an anaerobically polymerizable monomer as described in, for example, U.S. Pat. No. 3,218,305; Japanese Patent Publication Nos. 6545/'68; 852/'69 and 7541/'69 and these adhesives are widely used for locking of screw portions, sealing of pipes, etc., in various industrial fields. However, these anaerobic adhesives composed of a polyfunctional methacrylate as the main component have a disadvantage that screw portions locked using these adhesives are liable to loose under severe conditions that vibrations or impacts are always applied to these portions due to the low breakaway torque strength and further these adhesives cannot be used for the adhesion of flat members with each other, such as the adhesion of a metal plate and a metal plate since the adhesive power of the adhesives for such plates is very weak.
On the other hand, by using a carboxy group-containing compound as an anaerobically polymerizable monomer, adhesives showing a relatively high breakaway torque strength for the adhesion of screw portions are obtained as described in, for example, Japanese Patent Publication Nos. 31,680/'71; 9460/'73 and 41,437/'77 and Japanese Patent Publication (Unexamined) No. 86,937/'73 but the adhesion of flat members with each other is scarcely improved by these adhesives. Also, the aforesaid adhesives have a disadvantage that the metals adhered using the adhesives are corroded by the action of the carboxy group of the adhesives as well as have large disadvantages in the points of heat resistance, water resistance and stimulation of human skins.
Furthermore, U.S. Pat. No. 4,044,044, Japanese Patent Publication No. 39,694/'77 and Japanese Patent Publication (Unexamined) Nos. 83,572/'82; 90,074/'82 and 83,075/'83 describe that anaerobic adhesives having excellent adhesive strength are obtained by adding polymerizable organic acid phosphates having specific structures to polyfunctional methacrylates. However, these polymerizable acid phosphates have a fault of reducing the adhering rate of the one-part type anaerobic adhesives. Also, a polymerizable acid phosphate is usually prepared by the reaction of phosphorus pentaoxide and a polymerizable organic compound but there are difficulties in the preparation of the phosphates since phosphorus pentaoxide is very liable to change the quality thereof by the moisture in the air during the reaction and the reaction severely occurs.